The invention relates to thermoplastic molding compositions and more particularly to compositions containing graft rubbers.
A thermoplastic molding composition that contains a plurality of graft rubbers is disclosed. A first graft rubber is a product of emulsion polymerization of a mixture containing styrene and acrylonitrile in the presence of butadiene polymer latex (A) having an average particle diameter (d50) of 80 to 220 nm. An additional graft rubber is a product of emulsion polymerization of a mixture containing styrene and acrylonitrile in the presence of butadiene polymer latex (B) having an average particle diameter (d50) of 350 to 650 nm. The butadiene polymer latex (A) is the product of seed polymerization in which seed is butadiene polymer latex having a median particle diameter of 10 to 100 nm, and the butadiene polymer latex (B) is the product of agglomeration in which butadiene polymer latex (A) is the starting latex.
ABS molding compositions or molding compositions of the ABS type have for many years been used in large amounts as thermoplastic resins for the production of moldings of all kinds. The spectrum of properties of such resins can be varied within a wide range.
Particularly important properties of ABS molding compositions that may be mentioned are strength (impact strength, notched bar impact strength), modulus of elasticity, processability (MVR), dimensional stability under heat, surface gloss, defined combinations of properties generally being of importance depending on the field of use.
A particularly important feature for the processor of ABS molding compositions, especially where fully automated production plants are being used, is the constancy of properties or combinations of properties of the molding compositions to be processed.
Although it is possible by using modern processes in ABS production (e.g. computer-controlled polymerization and compounding) to produce products having relatively narrow tolerance limits, special applications require an even higher constancy of properties, which can be achieved only via the product composition or product structure.
The object was, therefore, to produce thermoplastic molding compositions of the ABS type that exhibit a very constant profile of properties. In particular, that was to be achieved for products having a very high surface gloss.